The present invention relates to a semiconductor waveguide device such as an electric absorption type optical intensity modulator (EA modulator), a supersaturated absorption device (SA device) or the like, and a manufacturing method thereof, and particularly to a structure in the neighborhood of an end face into which input light is launched.
Applications of such an EA modulator for various uses such as an optical gate, an optically controlled optical switch, etc. as well as for an electrooptical converter, have been discussed. Therefore, an increasing demand for a higher input light power allowable for the EA modulator has been expected.
A problem, however, arises in that when either input light power or a reverse voltage is increased at the EA modulator, a large photocurrent is produced in a core layer disposed in the neighborhood of a light-incident end face, and the temperature of the neighborhood thereof reaches a melting point of a semiconductor material, whereby a device is brought into destruction.
Particularly, a rib type (or ridge type) waveguide device having a channel structure is accompanied by a problem that since both sides of a ridged portion thereof are air or a polyimide filled layer, heat generated due to a photocurrent is hard to be radiated, and allowable input light power is low.